In a balanced iso the center tap is bonded to ground making it neutral potential. This lowers common mode noise , they also have emi /rfi filters. Nec art 647 shows what is allowed it’s on the website . I thought the use of a balanced transformer using a 230 phase to phase on primary helps in dc offset where most distortion of this type is from 125 phase to neural / ground types. in addition the large reduction of common mode noise I think is why this type product makes sense . If local even better but the method used to ground the secondary center tap matters . I think it needs to be a large over sized wire at main breaker bonding source in panel . Over sized utility pipe with a double clean ground clamps with above nec code gauge copper wire is needed. The rod or in some areas 2 rods must be at same bonding point .I would think a ground collector block works best. nec code dictates any form of isolation or change in voltage potential needs it’s own ground using building steel or building current grounding system. lastly I think audio in most cases should be in a phase to phase voltage potential in the USA of course. doing so greatly reduces many types of noise.
Thanks. I was addressing european rules, not the US National Electrical Code and just the safety issues.
Does the 230V Equi=tech have the CE certification label?